keysym(?Keysym, ?Key)

keysym/1 is true when KeysymSet is an atom giving the name of a pre-loaded keysym. The preloaded keysym sets are:

keysym/2 is true when Keysym is the integer, server-independent keysym for the the key named Key, which is an atom. In general, the name of a key is just the atom (quoted, if necessary). See the Xlib documentation on keysyms for a list of the keysyms and key names.